## Monday, January 28, 2008

### Funding woes hit UK astronomy hard

Very bad news for UK astronomy, or a "brighter future" by "withdraw[ing] from lower prority activities"? Putting the pitiful attempts at newspeak aside, this is definitely bad news.

## Thursday, January 10, 2008

### Senenmut would be proud

There are few, if any, sciences that have as much of a intimate relationship with time as astronomy does.

Because of the finite speed of light, we observe distant objects not as they are now but as they were long ago - millions of years ago in the case of nearby galaxies and billions of years ago for objects at higher redshift. By observing very large numbers of different objects, e.g. stars, we can follow all stages of their evolution that take millions or billions of years to occur in a single such object. Modern cosmology defines the age of Universe itself (13.7 billion years for a WMAP3 cosmology with H_0 = 71 km/s/Mpc, Omega_m = 0.27 and Omega_Lambda = 0.73).

In ancient days, at the dawn of human civilization several thousand years BCE, astronomy was as much about time as it is now. Agriculture, and hence civilization itself, relied upon careful timekeeping and nowhere more so than ancient Egypt where the annual Nile floods irrigated the land.

But we rarely see the personal side of ancient astronomy(*). Bojan Novakovic has written an interesting article on one ancient Egyptian astronomer: Senenmut (astro-ph/0801.1331), who was an important official in the reign of Queen Hatshepsut about 1500 BCE (today we would call Senenmut an over-achiever - he appears to have had an interesting life. See here and here).

The image on the left is a kneeling statue of Senemut at the Brooklyn Museum , taken by Keith Schengili-Roberts and licensed under the Creative Commons (found on wikipedia)

Were he alive today, Senenmut would probably in Austin, Texas, this week for the American Astronomical Society's annual winter meeting. He would no doubt be fascinated by the hundreds of talks and poster being presented there, and would probably discuss with colleagues (over coffee and a muffin) some of the major results being announced at the various press releases occurring at the meeting.

Would he be most interested in the Lyman-alpha-emitting galaxies discovered at high redshift that are the probably building blocks of today's massive spiral galaxies like our own Milky Way galaxy? Or would the detection of dust disks (which are possible planetary nurseries) around several stars that would otherwise be hundreds of millions of years too old to have such dust disks be the main topic of discussion? Perhaps, given his obvious political and managerial skills, Senenmut would mainly be discussing science politics and NASA funding.

But I'm sure that he'd be impressed with how far astronomy has come, and how fundamental a science it remains as.

(*) Ancient Greek astronomers are more well known. For example, Hipparchus (ca. 190 BCE to ca. 120 BCE) had the Hipparcos satellite named after him.

## Tuesday, January 08, 2008

### Is postmodernism dying? And would anyone be sad?

Big Monkey, Helpy Chalk (the nom de plume of a Philosophy Professor) outlines a retrospective on postmodernism and opines that it is a dying fad. Well worth a quick read. John Wilkins at Evolving Thoughts concurs, with a added caveat:

As concerns postmodernism, it always seemed to me that they had a strawman target. There never was a coherent tradition of "modernism", and I have long said that I don't know what it is that postmodernism is post- to, but that I am a prepostmodernist at heart. A friend shortened this to "preposterist".

There is a long standing reaction to "modernity", if by that we mean a scientific view of the world. It hasn't been helped by those who claim scientific standing for their own social or moral agendas, though. Marx, Engels, Lenin, Mao, Hitler and many others have all claimed that they, and nobody else, represents the true scientific approach. In the face of that, how can the ordinary person fail to be antimodern? And so they are - most people do not accept some or all of modern science. Antivaccinationists, creationists, astrologists, and so on all reject some aspect of the modern scientific consensus because they feel, as Theodore Roszak and others of the so-called New Left did, that it is somehow anti-human. I sympathise. But the fact is, that what they object to are trends that predate the modern world that simply dressed themselves in scientific garb.

Postmodernism always seemed to me to be a kind of epistemic nihilism. It's much easier to reject claims to knowledge that you object to if you can claim that there is no knowledge, just power and economics [emphasis mine]. How we know that, ironically, is not usually discussed by the postmodernists.

But even as (or if) postmodernism dies as an academic branch of philosophy its toxic legacy will contaminate modern society and politics for decades to come.

## Monday, January 07, 2008

### Winds, winds everywhere...

The current (January 1st 2008) edition of the Astrophysical Journal has two interesting papers that discuss galactic or AGN-driven winds.

Prochaska et al, 2008, ApJ, 672, 59 "On the Nature of Velocity Fields in High‐z Galaxies" discusses statistical analyzes of the velocity fields in damped Lyman alpha systems (extended gas in high redshift galaxies either seen spectroscopically in absorption along the line of sight to either a higher redshift AGN, or galaxies that are host to a Gamma Ray burst). They consider a variety of statistics drawn from various absorption lines, and conclude that:

The data support a scenario in which the statistic reflects dynamics in the interstellar medium (ISM) and W1526 traces motions outside the ISM (e.g., halo gas and galactic‐scale winds). The W1526 statistic and gas metallicity [M/H] are tightly correlated, especially for the QSO‐DLAs: with and . We argue that the W1526 statistic primarily tracks dynamical motions in the halos of high‐z galaxies and interpret this correlation as a mass‐metallicity relation with very similar slope to the trend observed in local, low‐metallicity galaxies. Finally, the GRB‐DLAs exhibit systematically larger W1526 values (>0.5 Å) than the QSO‐DLAs ( Å), which may suggest that galactic‐scale outflows contribute to the largest observed velocity fields.

Interesting stuff at first glance. It will be interesting to see how distinct a probe of galactic wind dynamics this method may prove, as compared to the blue-shifted nebular absorption lines seen directly in Lyman Break galaxy spectra.

The other paper, Ganguly & Brotherton, 2008, ApJ, 672, 102 "On the Fraction of Quasars with Outflows" is again based on absorption line studies, but this time on outflows intrinsic to the AGN. They conclude that about 60% of AGN display evidence of driving outflows, over a wide range of intrinsic AGN luminosity. Note that these outflows may be quite compact, perhaps as small as a few parsecs (compared to ~10+ kiloparsec-scale of starburst-driven galactic winds), even if they are similar or greater in absolute mechanical power.

## Tuesday, January 01, 2008

### A difficult job in difficult times: director of NASA's space science division

The NYT has an interesting article by Warren Leary on S. Alan Stern (seen here in official NASA uniform), who as associate administrator of NASA's space science division (official NASA biography here) has to make the difficult decisions on what to cut or deny to make the limited budget work:

Dr. Stern, an astrophysicist and planetary scientist, became associate administrator for NASA’s Science Mission Directorate in April. In an appearance before Congress the next month, he outlined a tough plan for keeping missions on budget and holding leaders responsible: better cost-estimating tools to more realistically price missions, more experience for scientists running projects, and new studies to better understand and reduce technology risks.

NASA devotes about $5.4 billion a year to its science program, divided among specialties like astrophysics, earth science and planetary exploration. To finance President Bush’s exploration initiative to return humans to the Moon, while also financing space shuttle operations and a shuttle replacement out of the agency’s approximately$16 billion annual budget, science program money is being held to about a 1 percent increase per year for four years.

Factoring in inflation and the loss of what had been anticipated financing increases, space experts say this amounts to a loss for NASA science of about \$3 billion over that period. For Dr. Stern, that means doing more with less.
Sounds like a stressful job, but someone has to do it.